The behavioral and neurochemical actions of four endogenous neuropeptides (neurotensin, TRH, bombesin and oxytocin) will be studied in detail to elucidate their mechanism and locus (neuroanatomical and neurochemical) of action in the central nervous system. The role of neurotensin, bombesin, and TRH in mediating physiological and behavioral thermoregulatory responses will be studied, as well as the role of these neuropeptides in the response of the organism to noxious stimulation. In addition the mechanism of action of neurotensin and bombesin in altering feeding behavior, the actions of ethanol and blockade of stress-induced gastric ulcers will be explored. Furthermore, the elucidation of specific neural circuits that contain neurotensin and TRH and their relation to conventional neurotransmitter systems (e.g. catecholamines) will be determined by combining lesion studies (electrolytic, kainic acid-induced, etc.) and sensitive radioimmunoassays for the peptides. The effects of physiological (altered ambient temperature, exposure to stressors, etc.) and pharmacological (ethanol, neuroleptics, etc.) manipulations on the concentration of neurotensin in specific regions within the central nervous system will be evaluated. The mechanism by which neurotensin alters activity of the mesolimbic dopamine system will be intensively studied in vitro and in vivo. The 2-deoxyglucose method will provide another sensitive index of peptide-induced changes in the functional activity of neural circuits in the central nervous system. Finally, the neuroanatomical loci where oxytocin induces maternal behavior and the specificity of this response will be intensively investigated. These studies, like those conducted during the tenure of the orginal research grant should provide valuable information concerning the brain-behavioral effects of peptides.